K35 Hot Pixels

Hello Arne and Tom

I am seeing lots of hot pixels in the SN2011DH images, with values of 28000 to 49000. Looked at fits header and temp is -37.66 on most images. Some at -38. Exposures at 300 secs. Some pixels are so hot that they confuse Maxim PT tool. Do we know what causes these. I do not remember them in the RR Tau images, nor the KK Oph pics. Its not always the same pixels, but quite often it is. Suggestions? Any known problems?